The tips of the tinsel-like coil things were covered with an even, light, sheen of frost, top to bottom. No chill-clogging nasty frost buildup. I pulled the panel behind the icemaker and the duct to the fridge has not a speck of frost on it, so that isn't it.

The coil underneath is fairly clean, so that isn't it either.

The evap fan works.

This is a no-muthaboard GE fridge, so no go there.

Could it be the tstat? If so, do I just pull the access panel, remove the connections and do a continuity check? (closed = chill, open = not-so-chill) The parts diagram shows it connected to a male and female "capilliary locator." I have no idea what those parts do, they are throwing doubt on my idea of just a simple continuity check to verify the tstat.